Department of Radiation Oncology, German Cancer Research Center and University of Heidelberg Medical Center, Heidelberg, Germany.
Radiat Oncol. 2010 Mar 26;5:25. doi: 10.1186/1748-717X-5-25.
Endothelial cells (EC) in tumor and normal tissue constitute critical radiotherapy targets. MicroRNAs have emerged as master switchers of the cellular transcriptome. Here, we seek to investigate the role of miRNAs in primary human dermal microvascular endothelial cells (HDMEC) after ionizing radiation.
The microRNA status in HDMEC after 2 Gy radiation treatment was measured using oligo-microarrays covering 361 miRNAs. To functionally analyze the role of radiation-induced differentially regulated miRNAs, cells were transfected with miRNA precursor or inhibitor constructs. Clonogenic survival and proliferation assays were performed.
Radiation up-regulated miRNA expression levels included let-7g, miR-16, miR-20a, miR-21 and miR-29c, while miR-18a, miR-125a, miR-127, miR-148b, miR-189 and miR-503 were down-regulated. We found that overexpression or inhibition of let-7g, miR-189, and miR-20a markedly influenced clonogenic survival and cell proliferation per se. Notably, the radiosensitivity of HDMEC was significantly influenced by differential expression of miR-125a, -127, -189, and let-7g. While miR-125a and miR-189 had a radioprotective effect, miR-127 and let-7g enhanced radiosensitivity in human endothelial cells.
Our data show that ionizing radiation changes microRNA levels in human endothelial cells and, moreover, exerts biological effects on cell growth and clonogenicity as validated in functional assays. The data also suggest that the miRNAs which are differentially expressed after radiation modulate the intrinsic radiosensitivity of endothelial cells in subsequent irradiations. This indicates that miRNAs are part of the innate response mechanism of the endothelium to radiation.
肿瘤和正常组织中的内皮细胞（EC）构成了放射治疗的关键靶点。microRNAs 已成为细胞转录组的主要调控开关。在这里，我们试图研究 microRNAs 在电离辐射后对原代人真皮微血管内皮细胞（HDMEC）的作用。
使用涵盖 361 个 microRNAs 的寡 microarray 测量 2 Gy 辐射处理后 HDMEC 中的 microRNA 状态。为了功能分析辐射诱导的差异调节 microRNAs 的作用，用 microRNA 前体或抑制剂构建体转染细胞。进行集落形成生存和增殖测定。
辐射上调了 microRNA 的表达水平，包括 let-7g、miR-16、miR-20a、miR-21 和 miR-29c，而 miR-18a、miR-125a、miR-127、miR-148b、miR-189 和 miR-503 则下调。我们发现，let-7g、miR-189 和 miR-20a 的过表达或抑制本身就明显影响集落形成生存和细胞增殖。值得注意的是，miR-125a、-127、-189 和 let-7g 的差异表达显著影响了 HDMEC 的放射敏感性。虽然 miR-125a 和 miR-189 具有放射保护作用，但 miR-127 和 let-7g 增强了人内皮细胞的放射敏感性。
我们的数据表明，电离辐射改变了人内皮细胞中的 microRNA 水平，并且，正如在功能测定中所验证的那样，对细胞生长和集落形成产生了生物学影响。这些数据还表明，辐射后差异表达的 microRNAs 调节内皮细胞在随后照射中的固有放射敏感性。这表明 microRNAs 是内皮细胞对辐射的先天反应机制的一部分。
